Studies on molecular structures and oligosaccharide-binding specificities of algal lectins

藻类凝集素的分子结构和寡糖结合特异性的研究

基本信息

批准号：
09460095
负责人：
HORI Kanji
金额：
$ 6.59万
依托单位：
Faculty of Applied Biological Science, Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

The research results showed that the lectins from twelve algal species examined have the highly binding specificity to some definite structures of oligosaccharides such as high-mannose type, complex type, or both type of N-glycans, forssman antigen, or sialyl Lewis X, respectively. The high-mannose or complex type N-glycan specific lectins were further divided into several groups by the difference of the branched structures recognized. The lectins thus recognize the branched moiety of the N-glycans. Interestingly, however, the reducing terminal N-acetylchitobiose of the N-glycans was essential for the binding of these lectins to the glycans, because they did not bind to any of the branched oligosaccharides themselves. Thus these algal lectins had the rigid binding specificity for some oligosaccharide structures.Among the high-mannose type N-glycan specific lectins, the complete primary structures of the lectins from the red alga Eucheuma serra and the blue-green alga Oscillatoria agard … More hii were determined. Both lectins had the very similar sequences to each other including the tandem repeat structures of homologous sequences of the N-terminal 67 amino acids. The number of the repeats was different between E.serra lectin (267 amino acids of 4 repeats) and O.agardhii lectin (132 amino acids of 2 repeats). On the other hand, the number of the repeats was well agreement with that of oligosaccharide-binding sites per a monomeric molecule for both lectins. The results indicate that a repeating unit corresponds to an oligosaccharide-recognition domain and the monomeric lectins agglutinate cells by having the multiple carbohydrate-binding sites on each single polypeptide chain. In homology search, surprisingly, the sequences of both algal lectins showed the very high similarity with that of a bacterium Myxococcus xanthus agglutinin including the four tandem repeats of the N-terminal 67 amino acids. Thus it found that a new lectin family having structural similarity was present among the lower organisms of the red alga, the blue-green alga (cyanobacterium) and the bacterium. This is the first example that the structural similarity of lectin molecules was found between prokaryote and eukaryote organisms. Less

研究结果表明，所检查的十二种藻类的讲座具有高度结合的特异性，该特异性分别与寡糖的某些确定结构，例如高臭糖类型，复杂类型或两种类型的N-聚糖，福斯曼抗原或Siallyl Lewis X。通过公认的分支结构的差异，高甘露糖或复杂的N-聚糖特异性讲座进一步分为几组。然而，有趣的是，N-Glycans的还原末端N-乙酰基二碱对这些讲座与Glycans的结合至关重要，因为它们没有与任何分支的寡糖本身结合。这些藻类讲座具有某些寡糖结构的刚性结合特异性。在高甘露糖型的N-聚糖特定讲座中，来自红色藻类Eucheuma Serra和蓝绿色藻类振荡振荡的完整的演讲的完整主要结构……确定了更多HII。两种讲座的序列都非常相似，包括N末端67氨基酸的同源序列的串联重复结构。 E.Serra讲座（267个重复氨基酸的氨基酸）和O.Agardhii讲座（132个氨基酸为2个重复序列）之间的重复数量不同。另一方面，重复的数量与每两个讲座单体分子的寡糖结合位点的数量都很好。结果表明，重复单元对应于寡糖识别结构域，单体讲座通过在每个单一多肽链上具有多个碳水化合物结合位点，从而凝结着细胞。在同源性搜索中，令人惊讶的是，两种藻类讲座的序列都表明，与细菌粘粒蛋白蛋白的相似性非常高，包括N末端67氨基酸的四个串联重复序列。它发现，在红藻，蓝绿色藻类（蓝细菌）和细菌的较低生物中存在一个具有结构相似性的新讲座家族。这是第一个例子，即在原核生物和真核生物生物之间发现了讲座分子的结构相似性。较少的